Adsorption and photocatalytic degradation of 2-chlorophenol in water: Evaluating the performance of TiO2/activated carbon vs. using a mixture of TiO2 and activated carbon

Abstract

The work reported here compared between two photocatalytic degradation strategies of 2-chlorophenol (2-CP). The first strategy utilized titanium dioxide (TiO₂) immobilized on activated carbons (AC) to produce TiO₂/AC photocatalysts of various TiO₂ loadings. Various immobilization techniques were used: chemical vapour deposition (CVD), direct air hydrolysis (DAH), high-temperature impregnation (HTI). In the first strategy, characterization, adsorption and photocatalytic degradation of 2-CP using TiO₂/AC revealed that: 1) deposition of anatase TiO₂ occurred in the micro pores of AC; 2) adsorption capacity decreased with increasing anatase TiO₂ loading on TiO₂/AC; 3) adsorption kinetics followed pseudo first order kinetics where 40 % of 2-CP was adsorbed; 4) photocatalytic degradation caused removal of all 2-CP and 80 % of total organic carbon (TOC), while no chloride ion (Cl⁻) was produced. In the second strategy, naked TiO₂ (anatase) and mixtures of (anatase and AC) were involved to investigate the effect of presence of AC on degradation ability of anatase TiO₂ towards 2-CP. The results showed that: 1) naked TiO₂ (anatase) caused better degradation of 2-CP than TiO₂/AC (Cl⁻ was liberated; complete degradation of 2-CP occurred; some TOC remained in the suspension); 2) presence of AC with anatase TiO₂ in the reaction mixture negatively affected Cl⁻ production, but positively affected 2-CP and TOC disappearance; 3) when all 2-CP was adsorbed on AC, production of Cl⁻ was inhibited but continued at a reduced rate. This might indicat that both dissolved and adsorbed 2-CP contributed to the degradation process.